The role of party-pooper can be the greatest of fun and Bath are becoming adept. They spoiled the first St George's Day game at Twickenham for Wasps a year ago and yesterday they repeated the dose.

The destroyer in chief was Tom Biggs, with his first hat-trick for the club. Where the New Zealander Joe Maddock scored three tries in 2010, the former Leeds wing – who has played at Twickenham for England's sevens team – repeated the feat and earned Bath a bonus point before half-time.

With two games in the Aviva Premiership to go, Bath have guaranteed Heineken Cup rugby next season, at the same time obliterating what faint hopes Wasps had of gracing a tournament they have twice won. Bath also demonstrated the quality of rugby that Steve Meehan, their departing head coach, has sought over the last five years.

They scored so heavily because, where they boasted experience, Wasps had callow youth. That may be hard on Joe Launchbury, a 20-year-old lock who distinguished himself in the hoary company of Danny Grewcock (38), Simon Shaw (37) and Ignacio Fernandez Lobbe (36), but two teenagers, the full-back Elliot Daly and No 8 Billy Vunipola, will have learned much of what it takes to enjoy a successful career in the top flight.

Among Bath's old heads was, of course, Lewis Moody, the England captain making a first start since January after overcoming the knee problems which kept him out of the Six Nations. Moody left the field early in the second half, having carried into the game a knock on his knee suffered on Friday, but Bath's coaching staff have no doubt of his fitness to play in the remaining games, both against Newcastle.

"Lewis probably wouldn't have played much longer anyway," Meehan said. "He just wanted to get some tough training in, give himself some confidence." Moody would have derived plenty of that from the accuracy of his colleagues, notably at the breakdown where they forced a string of turnovers, and at the scrum, which allowed Michael Claassens to orchestrate matters superbly. Time after time they exploited naïvety in the Wasps defence and it seems inevitable that Wasps will conclude the season in their worst position since the Premiership began in 1998. Their travails began in the fourth minute, when Matt Carraro slashed through and Nick Abendanon popped up a pass from which Biggs scored.

Simon Taylor and Carraro were both denied tries after being held up over the line but after Sam Vesty kicked a penalty, Bath went to town. From their own 22, Claassens sent Matt Banahan motoring into space and the England player sent Biggs to the line. David Walder put Wasps on the scoreboard with a penalty somewhat harshly awarded against Lee Mears but it was no more than a blip on the radar.

Claassens, with a classical dummy, opened the way for Banahan to score but the best was reserved for just before the interval. Zak Taulafo knocked on, Claasens found Mears, Taylor and Vesty in supporting roles and Biggs had scope to beat Daly and, twice, Richard Haughton en route to his third try.

"I guess the game was over at half-time," said Leon Holden, whose hat is in the ring for a permanent role as director of rugby at Wasps. "We probably had our best training week of the whole year but if you turn ball over after only two or three phases, as we did, you're going to lose. A side like Bath are one of the best in England for stinging you from turnovers."

Nevertheless, Holden kept his young men on the field, knowing they will only be better for the experience. He said that Launchbury is an England lock of the future, that Daly has the X-factor and that Vunipola played well in unforgiving circumstances.

Bath had scored a fifth try, Banahan collecting Vesty's chip after the fly-half had swayed through the cover, before Wasps found their own way to the line. Almost inevitably the try came from Joe Simpson, the scrum half running from his own 10-metre line and relying on his speed to out-distance the Bath defenders.

It was, though, no more than a gesture. Bath, all composure, kept forcing the errors and Biggs, happy with his own haul, sent through a side-footed kick for Carraro to collect and score. It was, then a bittersweet moment as Wasps thanked the 38,000 crowd (down by some way on last year's attendance of more than 60,000) that veterans like David Walder, Mark van Gisbergen and Serge Betsen will depart next month, leaving the field to youth.